class_docstr: Multi-level fused semantic segmentation head.
  
  .. code-block:: none
  
      in_1 -> 1x1 conv ---
                          |
      in_2 -> 1x1 conv -- |
                         ||
      in_3 -> 1x1 conv - ||
                        |||                  /-> 1x1 conv (mask prediction)
      in_4 -> 1x1 conv -----> 3x3 convs (*4)
                          |                  \-> 1x1 conv (feature)
      in_5 -> 1x1 conv ---
code: def loss(self, mask_pred, labels):
      labels = labels.squeeze(1).long()
      loss_semantic_seg = self.criterion(mask_pred, labels)
      loss_semantic_seg *= self.loss_weight
      return loss_semantic_seg
  
file_path: insightface/detection/scrfd/mmdet/models/roi_heads/mask_heads/fused_semantic_head.py
imports: import torch.nn
  import torch.nn.functional
  from mmcv.cnn import ConvModule, kaiming_init
  from mmcv.runner import auto_fp16, force_fp32
  from mmdet.models.builder import HEADS
label_desc: Use image node_id 4 for calling the FusedSemanticHead obj's underlying member method code with example usage: obj.loss(mask_pred, labels) and returns: loss_semantic_seg